Power Module Resin Detachment Prevention via Segmented Adhesion
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Solution Overview
Problem
Conventional power modules face issues with resin detachment due to thermal stress caused by differing linear expansion coefficients between semiconductor elements and interconnection materials, leading to compromised insulation and module functionality.
Innovation Solution
A power module design that incorporates a clearance portion between the sealing resin and the interconnection material, utilizing a joining material with weak adhesion to the resin, and a process to decrease adhesion force on the interconnection material's surface, allowing for stress relaxation and preventing resin detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sealing resin is used to mechanically bind the power semiconductor element and interconnection material, then the joining strength is improved, but the resin may detach from the power semiconductor element due to thermal stress
Solution Approach 1:
The sealing resin is divided into multiple regions with different adhesion characteristics: a first region with strong adhesion to the power semiconductor element and a second region with weak adhesion to the interconnection material. This segmentation allows the resin to firmly secure the semiconductor element while detaching from the interconnection material to avoid thermal stress concentration, thereby maintaining both joining strength and insulation reliability.
Solution Approach 2:
Different adhesion properties are assigned to different locations of the sealing resin. The first region contacting the power semiconductor element has strong adhesion force to ensure secure binding, while the second region contacting the interconnection material has weak adhesion force to allow stress relaxation. This local differentiation resolves the contradiction between maintaining strong joining and preventing detachment under thermal stress.
2Manufacturing precision
If the sealing resin is cured under application of pressure, then the insulation sealing is improved, but the resin may detach from the power semiconductor element when temperature fluctuates
Solution Approach 1:
The sealing resin is segmented into regions with different adhesion characteristics. The first region maintains strong adhesion to the power semiconductor element to ensure stable binding, while the second region has weak adhesion to the interconnection material to allow detachment under thermal stress. This segmentation enables the resin to maintain insulation sealing quality while resisting detachment during temperature fluctuations.
Solution Approach 2:
The weak adhesion between the sealing resin and interconnection material, which might seem detrimental to bonding strength, actually serves as a beneficial stress relief mechanism. When temperature fluctuates, the resin can detach from the interconnection material rather than the power semiconductor element, converting the potential harm of weak adhesion into the benefit of protecting the critical semiconductor-element-resin interface.
3Strength
If a polyimide film is formed on the power semiconductor element to prevent resin detachment, then the adhesion force is improved, but the manufacturing process becomes complicated
Solution Approach 1:
The patent extracts and eliminates the need for the polyimide film intermediate layer by directly designing the sealing resin with spatially differentiated adhesion properties. Instead of adding a separate film layer to enhance adhesion, the resin itself is configured to have strong adhesion to the power semiconductor element and weak adhesion to the interconnection material, simplifying the manufacturing process while maintaining or improving adhesion strength.
Solution Approach 2:
The adhesion parameters of the sealing resin are changed spatially rather than adding a separate material layer. By modifying the adhesion force parameter of the resin at different locations (strong at the semiconductor interface, weak at the interconnection material interface), the patent achieves the desired adhesion strength without introducing additional manufacturing steps such as polyimide film formation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively reduces the likelihood of resin detachment, maintaining insulation integrity and module functionality by relaxing thermal stress at the interface between the semiconductor element and the sealing resin.
Implementation Method 1
a curable sealing resin is used as an insulation sealing for the power module to mechanically bind the power semiconductor element, the joining material, and the plate-like interconnection material
Implementation Method 2
The joining material is formed between the first electrode and the interconnection material to electrically and mechanically connect the first electrode to the interconnection material
Implementation Method 3
The joining material is formed between the first electrode and the interconnection material to electrically and mechanically connect the first electrode to the interconnection material
Implementation Method 4
The circuit board is disposed to face the second surface of the power semiconductor element and is electrically and mechanically connected to the second electrode
Implementation Method 5
The circuit board is disposed to face the second surface of the power semiconductor element and is electrically and mechanically connected to the second electrode
Data Source
AI summary
A power module includes a power semiconductor element, an interconnection material, a circuit board, an external terminal, a joining material, and a sealing resin. A clearance portion is continuously formed between the sealing resin and each of an end surface of the joining material and a surface of the interconnection material so as to extend from the end surface of the joining material to the surface of the interconnection material, the end surface of the joining material being located between the power semiconductor element and the interconnection material, the surface of the interconnection material being located between the end surface and a predetermined position of the interconnection material separated by a distance from the end surface.